Many search engine services, such as Google, Yahoo!, and MSN, provide for searching for information that is accessible via the Internet. These search engine services allow users to search for web pages and other Internet-accessible resources that may be of interest to users. After a user submits a search request that includes search terms, the search engine service identifies web pages that may be related to those search terms. The collection of web pages that most closely match the search terms is referred to as the “search result.” The search engine service then ranks the web pages of the search result based on the closeness of each match, web page popularity (e.g., Google's page ranking), and so on. The search engine service then displays to the user links to those information sources in an order that is based on their rankings.
Some search engine services do not charge a fee to users or to the providers of web pages for including links to their web pages in search results. Rather, the search engine services obtain revenue by placing advertisements along with search results and charging the advertisers when a user selects an advertisement. These paid-for advertisements are commonly referred to as “sponsored links,” “sponsored matches,” or “paid-for search results.” An advertiser who wants to place an advertisement along with certain search results provides a search engine service with an advertisement set that includes a creative (or advertisement), a keyword, and a link to a landing page of the advertiser. Advertisers often refer to banner advertisements and other forms of created advertisements as a “creative.” When a search request is received, the search engine service identifies the advertisement sets whose keywords match those of the search request. The search engine service then may display the creative (which may include the link to the landing page) of some of the advertisement sets along with the search results. When a user clicks on a creative (e.g., a “clickthrough”) to visit the landing page, the search engine service may charge a fee to the advertiser.
Advertisers use various techniques to identify words or phrases that may be potentially good keywords for advertisement sets. One such technique analyzes queries submitted to a web site by users searching for products to purchase. If certain queries tend to result in significant financial benefit (e.g., significant profits or higher conversion rate), then the words of those queries may be good keywords. A user who submits a query to a general search engine service, however, may have reasons for submitting the query other than for purchasing a product related to the query. For example, a person who submits the name of a song as a query may be interested in locating the lyrics of the song, and not interested in buying a CD containing the song. As such, queries that are selected from product searches sometimes do not perform as well as an advertiser might expect when used as keywords of advertisement sets submitted to a general search engine service.